The aim of this research is to determine the biochemical basis of interferon action. Our work has focused on 2'5'-isooligoadenylic acid synthetase and a protein kinase activity which phosphorylates a 67,000 dalton protein, two enzymatic activities which are induced by interferon and enhanced by some double-stranded ribonucleic acids (dsRNA). The work has been divided into two studies: 1) The relationship of polynucleotide structure to the activation of 67K protein kinase activity and protein synthesis inhibition and 2) the role of oligo A synthetase in the establishment and maintenance of the anti-viral effects of interferon.